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\begin{tabular}{lcccc} \hline
 & (1) & (2) & (3) & (4) \\
VARIABLES & ratification & ratification & ratification & ratification \\ \hline
 &  &  &  &  \\
IO membership & 0.011** &  &  &  \\
 & (0.004) &  &  &  \\
ln trade intensity & -0.125* & -0.132* & -0.037 & -0.120* \\
 & (0.054) & (0.054) & (0.049) & (0.057) \\
democracy, polity & 0.010+ & 0.011+ & 0.016* & 0.011+ \\
 & (0.006) & (0.006) & (0.006) & (0.006) \\
ln GDP pc & 0.931 & 0.999 & 0.467 & 1.003 \\
 & (0.617) & (0.617) & (0.654) & (0.638) \\
ln GDP pc squared & -0.039 & -0.044 & -0.013 & -0.044 \\
 & (0.037) & (0.037) & (0.040) & (0.039) \\
log of SO2 per capita & 0.090** & 0.092** & 0.054 & 0.092** \\
 & (0.034) & (0.034) & (0.035) & (0.035) \\
no countries ratified & 0.023** & 0.023** & 0.022** & 0.023** \\
 & (0.002) & (0.002) & (0.002) & (0.002) \\
lag \% of countries in my income group that have already ratified this treaty & 0.000 & 0.000 & 0.001 & 0.001 \\
 & (0.004) & (0.004) & (0.004) & (0.004) \\
\% of countries in my region that have already ratified this treaty up to previou & 0.030** & 0.030** & 0.031** & 0.031** \\
 & (0.002) & (0.002) & (0.002) & (0.002) \\
log of plein GDP & -0.073 & -0.080 & 0.057 & -0.060 \\
 & (0.070) & (0.068) & (0.061) & (0.072) \\
country lies in Africa & -0.506** & -0.527** & -0.412** & -0.455** \\
 & (0.147) & (0.147) & (0.158) & (0.148) \\
North America & -0.547** & -0.506** & -0.703** & -0.582** \\
 & (0.158) & (0.158) & (0.189) & (0.167) \\
Latin America & -0.543** & -0.541** & -0.478** & -0.523** \\
 & (0.124) & (0.124) & (0.129) & (0.124) \\
country lies in east Asia & -0.461** & -0.420** & -0.683** & -0.481** \\
 & (0.140) & (0.144) & (0.164) & (0.145) \\
country lies in west Asia & -0.713** & -0.711** & -0.789** & -0.696** \\
 & (0.159) & (0.159) & (0.167) & (0.164) \\
time & -0.328** & -0.328** & -0.329** & -0.328** \\
 & (0.017) & (0.017) & (0.017) & (0.017) \\
time squared & 0.010** & 0.010** & 0.010** & 0.010** \\
 & (0.001) & (0.001) & (0.001) & (0.001) \\
time cubed & -0.000** & -0.000** & -0.000** & -0.000** \\
 & (0.000) & (0.000) & (0.000) & (0.000) \\
formals\_sum\_member &  & 0.013** &  &  \\
 &  & (0.004) &  &  \\
informals\_sum\_member &  &  & 0.001 &  \\
 &  &  & (0.007) &  \\
total\_sum\_member &  &  &  & 0.008* \\
 &  &  &  & (0.003) \\
Constant & -9.394** & -9.645** & -8.396** & -9.759** \\
 & (2.970) & (2.974) & (3.105) & (3.022) \\
 &  &  &  &  \\
Observations & 574,196 & 574,196 & 574,196 & 574,196 \\
r2\_p & 0.197 & 0.197 & 0.195 & 0.196 \\
ll & -27208 & -27199 & -27257 & -27221 \\
 N\_clust & 155 & 155 & 155 & 155 \\ \hline
\multicolumn{5}{c}{ Robust standard errors in parentheses} \\
\multicolumn{5}{c}{ ** p$<$0.01, * p$<$0.05, + p$<$0.1} \\
\end{tabular}
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